From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754482AbeDQQzV (ORCPT ); Tue, 17 Apr 2018 12:55:21 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:33830 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754454AbeDQQzQ (ORCPT ); Tue, 17 Apr 2018 12:55:16 -0400 Subject: Re: [PATCH v4 05/15] KVM: s390: enable/disable AP interpretive execution To: Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, buendgen@de.ibm.com Cc: freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, berrange@redhat.com, fiuczy@linux.vnet.ibm.com References: <1523827345-11600-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1523827345-11600-6-git-send-email-akrowiak@linux.vnet.ibm.com> <15b60572-40d6-0f03-11f9-c50cb7eb00e8@linux.vnet.ibm.com> <6cba35df-b0de-8000-bb39-c4cec8622c57@linux.vnet.ibm.com> <2b053349-071e-17ed-6ebd-a37bcfd2f330@linux.vnet.ibm.com> From: Pierre Morel Date: Tue, 17 Apr 2018 18:55:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <2b053349-071e-17ed-6ebd-a37bcfd2f330@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18041716-0040-0000-0000-0000044E9A02 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18041716-0041-0000-0000-000020F2E36E Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-17_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804170148 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/04/2018 18:22, Tony Krowiak wrote: > On 04/17/2018 12:13 PM, Pierre Morel wrote: >> On 17/04/2018 17:02, Tony Krowiak wrote: >>> On 04/16/2018 06:51 AM, Pierre Morel wrote: >>>> On 15/04/2018 23:22, Tony Krowiak wrote: >>>>> The VFIO AP device model exploits interpretive execution of AP >>>>> instructions (APIE) to provide guests passthrough access to AP >>>>> devices. This patch introduces a new interface to enable and >>>>> disable APIE. >>>>> >>>>> Signed-off-by: Tony Krowiak >>>>> --- >>>>>   arch/s390/include/asm/kvm-ap.h   |   16 ++++++++++++++++ >>>>>   arch/s390/include/asm/kvm_host.h |    1 + >>>>>   arch/s390/kvm/kvm-ap.c           |   20 ++++++++++++++++++++ >>>>>   arch/s390/kvm/kvm-s390.c         |    9 +++++++++ >>>>>   4 files changed, 46 insertions(+), 0 deletions(-) >>>>> >>>>> diff --git a/arch/s390/include/asm/kvm-ap.h >>>>> b/arch/s390/include/asm/kvm-ap.h >>>>> index 736e93e..a6c092e 100644 >>>>> --- a/arch/s390/include/asm/kvm-ap.h >>>>> +++ b/arch/s390/include/asm/kvm-ap.h >>>>> @@ -35,4 +35,20 @@ >>>>>    */ >>>>>   void kvm_ap_build_crycbd(struct kvm *kvm); >>>>> >>>>> +/** >>>>> + * kvm_ap_interpret_instructions >>>>> + * >>>>> + * Indicate whether AP instructions shall be interpreted. If they >>>>> are not >>>>> + * interpreted, all AP instructions will be intercepted and >>>>> routed back to >>>>> + * userspace. >>>>> + * >>>>> + * @kvm: the virtual machine attributes >>>>> + * @enable: indicates whether AP instructions are to be >>>>> interpreted (true) or >>>>> + *        or not (false). >>>>> + * >>>>> + * Returns 0 if completed successfully; otherwise, returns >>>>> -EOPNOTSUPP >>>>> + * indicating that AP instructions are not installed on the guest. >>>>> + */ >>>>> +int kvm_ap_interpret_instructions(struct kvm *kvm, bool enable); >>>>> + >>>>>   #endif /* _ASM_KVM_AP */ >>>>> diff --git a/arch/s390/include/asm/kvm_host.h >>>>> b/arch/s390/include/asm/kvm_host.h >>>>> index 3162783..5470685 100644 >>>>> --- a/arch/s390/include/asm/kvm_host.h >>>>> +++ b/arch/s390/include/asm/kvm_host.h >>>>> @@ -715,6 +715,7 @@ struct kvm_s390_crypto { >>>>>       __u32 crycbd; >>>>>       __u8 aes_kw; >>>>>       __u8 dea_kw; >>>>> +    __u8 apie; >>>>>   }; >>>>> >>>>>   #define APCB0_MASK_SIZE 1 >>>>> diff --git a/arch/s390/kvm/kvm-ap.c b/arch/s390/kvm/kvm-ap.c >>>>> index 991bae4..55d11b5 100644 >>>>> --- a/arch/s390/kvm/kvm-ap.c >>>>> +++ b/arch/s390/kvm/kvm-ap.c >>>>> @@ -58,3 +58,23 @@ void kvm_ap_build_crycbd(struct kvm *kvm) >>>>>       } >>>>>   } >>>>>   EXPORT_SYMBOL(kvm_ap_build_crycbd); >>>>> + >>>>> +int kvm_ap_interpret_instructions(struct kvm *kvm, bool enable) >>>>> +{ >>>>> +    int ret = 0; >>>>> + >>>>> +    mutex_lock(&kvm->lock); >>>>> + >>>>> +    if (!test_kvm_cpu_feat(kvm, KVM_S390_VM_CPU_FEAT_AP)) { >>>> >>>> Do we really need to test CPU_FEAT_AP? >>> >>> Yes we do. >> >> really? why? > > The KVM_S390_VM_CPU_FEAT_AP will not be enabled by KVM if the AP > instructions are not installed on the host. I assume - but have > no way of verifying - that if the AP instructions are not installed > on the host, that interpretation would fail. Do you know what would > happen if AP instructions are interpreted when not installed on > the host? If the host has no AP instructions (his ECA.28=0) but it set ECA.28 for a guest, there will be no AP instructions available in the guest. > >> >> >>> >>>> >>>> >>>> I understand that KVM_S390_VM_CPU_FEAT_AP means AP instructions are >>>> interpreted. >>>> shouldn't we add this information in the name? >>>> like KVM_S390_VM_CPU_FEAT_APIE >>> >>> KVM_S390_VM_CPU_FEAT_AP does NOT mean AP instructions are >>> interpreted, it means >>> AP instructions are installed. >> >> Right same error I made all along this review. >> But AFAIK it means AP instructions are provided to the guest. >> Then should this function be called if the guest has no AP >> instructions ? >> >> >>> >>>> >>>>> +        ret = -EOPNOTSUPP; >>>>> +        goto done; >>>>> +    } >>>>> + >>>>> +    kvm->arch.crypto.apie = enable; >>>>> +    kvm_s390_vcpu_crypto_reset_all(kvm); >>>>> + >>>>> +done: >>>>> +    mutex_unlock(&kvm->lock); >>>>> +    return ret; >>>>> +} >>>>> +EXPORT_SYMBOL(kvm_ap_interpret_instructions); >>>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >>>>> index 55cd897..1dc8566 100644 >>>>> --- a/arch/s390/kvm/kvm-s390.c >>>>> +++ b/arch/s390/kvm/kvm-s390.c >>>>> @@ -1901,6 +1901,9 @@ static void kvm_s390_crypto_init(struct kvm >>>>> *kvm) >>>>>       kvm->arch.crypto.crycb = &kvm->arch.sie_page2->crycb; >>>>>       kvm_ap_build_crycbd(kvm); >>>>> >>>>> +    /* Default setting indicating SIE shall interpret AP >>>>> instructions */ >>>>> +    kvm->arch.crypto.apie = 1; >>>>> + >>>>>       if (!test_kvm_facility(kvm, 76)) >>>>>           return; >>>>> >>>>> @@ -2434,6 +2437,12 @@ static void >>>>> kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu) >>>>>   { >>>>>       vcpu->arch.sie_block->crycbd = vcpu->kvm->arch.crypto.crycbd; >>>>> >>>>> +    vcpu->arch.sie_block->eca &= ~ECA_APIE; >>>>> +    if (vcpu->kvm->arch.crypto.apie && >>>>> +        test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_AP)) >>>> >>>> Do we call xxx_crypto_setup() if KVM does not support AP >>>> interpretation? >>> >>> Yes, kvm_s390_vcpu_crypto_setup(vcpu) is called by >>> kvm_arch_vcpu_setup(vcpu) >>> as well as from kvm_s390_vcpu_crypto_reset_all(kvm). Calling it has >>> nothing >>> to do with whether AP interpretation is supported or not as it does >>> much >>> more than that, including setting up of wrapping keys and the CRYCBD. >> >> Sorry, still the same error I made about CPU_FEAT_AP meaning AP >> instructions in the guest >> and not AP interpretation available. >> Could apie be set if AP instruction are not supported? >> >>> >>>> >>>>> + vcpu->arch.sie_block->eca |= ECA_APIE; >>>>> + >>>>> + >>>>>       if (!test_kvm_facility(vcpu->kvm, 76)) >>>>>           return; >>>>> >>>> >>> >> > -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany